Background. With insufficient information about the importance of melatonin in human physiology, this hormone is known to be associated with sleep, mood, reproduction, tumor development, and aging. Chronic sleep problems, stress, fatigue, irritability, confusion, tension, and depressive symptoms can be observed in melatonin deficiency. There is no such study in the literature and it is thought to shed light on the literature. The purpose of the study is to examine the relationship between melatonin level and religious orientation, depression level, and sleep quality of students in nursing and different department. Materials and methods. This cross-sectional study was conducted between April 2019 and April 2020. The target population of the study consisted of 1200 students who studying in 2nd grade to ensure harmony and homogeneity in stress, sleep, and melatonin parameters. The sample of the study consisted of 145 individuals who accepted to participate in the study among the 2nd-grade students. Descriptive Information Form, Religious Orientation Scale, Beck Depression Inventory, and Pittsburg Sleep Quality Index (PSQI) scale were used to collect research data. Results. According to the findings obtained from the study, it was determined that the melatonin level of the students was 0.79±0.52 pg/ml, the total score mean of the Sleep Quality Scale was 7.24±3.35, the Beck Depression Inventory was 16.40±10.84 and the Religious Orientation Scale was 47.41±6.05. It was determined that their sleep quality was “bad”; moderately depressed and religious orientation and the melatonin level was below normal. Conclusions. Since the sleep quality total score of the students was above 5, it was determined that their sleep quality was “bad”. It was found that the group was moderately depressed and had a moderate religious orientation. In the study where the standard was accepted as 0.90, it was found that the melatonin level was below normal. It is recommended that the study be conducted in larger groups.